The paper describes the theory and practice of low-temperature decomposition of alumina solutions. Scientific substantiation of the use of activated nepheline solution as an inoculum for HASN crystallization is given. Materials of experimental study of chemical equilibrium and kinetics of the decomposition process in the system activated nepheline alcohol - aluminate solution are presented. The possibility of achieving technological low-temperature factors of the process sufficient for the subsequent complete deposition of silica is shown.
Materials explaining the mechanism of spatial differentiation of solution composition with the participation of the gas phase and its role in the creation of non-equilibrium conditions that ensure recrystallization of solid products are presented. Calculations of equilibrium in a number of systems of alumina production are presented. Indicators of non-equilibrium of solutions and their dependence on the leading technological parameters of the process are established.
The mechanism of mass crystallization of synthetic gibbsite at decomposition of aluminate solutions is proposed. The leading role of nucleation and supersaturation in the formation of granulometry of aluminum hydroxide precipitate is shown. The methodology and experimental results of induction period determination during gibbsite precipitation from aluminate solution are presented. The surface energy of solid phase formation during carbonization of aluminate solution as a function of critical nucleation size is determined.
